Systems and methods for measuring and controlling fluid flow in a system are found in various industries. For example, various air distribution systems in commercial aircraft include various devices for measuring and controlling the flow of air through numerous branch lines that feed different portions of the aircraft. The flow of air through these branch lines is, in many instances controlled by a control valve, in response to a flowrate measurement.
For example, one or more of the branch lines in an aircraft air distribution system may include a duct having a flow venturi disposed therein. A flow venturi, as is generally known, may be used to sense fluid flowrate, and typically includes an upstream convergent section, a downstream divergent section, and an interposed flow constricting throat. The change in cross-sectional flow area in the flow venturi causes a pressure change between the convergent section and the flow constricting throat. This change in pressure is sensed and is used to measure fluid flowrate through the duct. In response to the measured flowrate, a control valve, which may be mounted on the duct downstream of the flow venturi, may then be positioned to control the fluid flowrate to a commanded magnitude.
In some systems, including various ones of the aircraft air distribution systems mentioned above, increased flowrate measurement accuracy and controllability is being demanded. In some systems such demands may be realized by reducing the cross sectional flow area of the interposed constricting throat in the existing flow venturi. However, many conventional techniques for reducing the cross sectional flow area a sufficient amount to meet the increased flowrate measurement accuracy and controllability demands may rely on significant redesign of the flow duct, which can be relatively costly and time consuming.
Hence, there is a need for a method of reducing the cross sectional flow area of a venturi flow constricting throat a sufficient amount to meet increased flowrate measurement accuracy and controllability demands that does not rely on a relatively costly and/or time consuming redesign. The present invention addresses at least this need.